Filter press



Sept. 17, 1968 J. D. FANN 3,401,802

FILTER PRESS Original Filed Feb. 1 1965 4/3079; .5. Fer/7n I N VEN TOR.

ATTORNEY United States Patent 3,401,802 FILTER PRESS James D. Faun, 3202Argonne, Houston, Tex. 77006 Original application Feb. 1, 1965, Ser. No.429,397, now

Patent No. 3,371,786, dated Mar. 5, 1968. Divided and this applicationAug. 8, 1967, Ser. No. 659,066

2 Claims. (Cl. 210-446) ABSTRACT OF THE DISCLOSURE A filter pressapparatus of the type wherein filter media is held in position over anend of a filter chamber and liquid within the filter chamber is filteredoutwardly from the filter chamber through the filter media, theapparatus including seal means at the filter media and receiver meansfor the filtrate.

This application is a division of application Ser. No. 429,397, filedFeb. 1, 1965, by James D. Fann and entitled, Filter Press, now PatentNo. 3,371,786.

This invention relates to filtering apparatus and more particularly toimproved filter apparatus for removing solids from a liquid underpressure.

Various liquids containing suspended solids, such as drill muds used inoil and gas well boreholes, are tested by filtration to predict theirbehavior characteristics under operating conditions. In the testing ofdrill muds, for example, filtration is preferably conducted underdifferential pressure conditions to simulate as closely as possiblepressure conditions in a borehole where the fluid may be used. Onemethod employed to remove solids from a liquid under differentialpressure conditions involves placing a test specimen of the liquid in acontainer which is provided with a filter medium. The filter mediumcommunicates with a filtrate line through which a liquid after removalof solids may be discharged from the container. A pressure source isconnected through an adjustable constant pressure discharge regulator tothe container for generating a head pressure on the liquid, a head pressure being a pressure which tends to force the liquid containingsuspended solids through the filter medium. A second pressure source isconnected through a second adjustable constant pressure dischargeregulator to the filtrate discharge line for creating a back pressure onthe liquid, a back pressure being one which tends to oppose movement ofthe liquid through the filter medium. Frequently, however, in thetesting of a liquid containing suspended solids, a back pressure will beapplied to the liquid which is greater than the head pressure due tomaladjustment of the back pressure regulator, causing the liquid to bedischarged out of the container into the head pressure regulator.Discharge of liquid into a head pressure regulator can both render theregulator inoperable and cause data from tests being run to beinaccurate.

Additionally, receptacles for receiving filtrate from the container aregenerally subject to the back pressure of the apparatus and glass orplastic level gauges generally employed with these receptacles can beshattered due to maladjustments of the back pressure resulting ininjuries to operating personnel.

Typical prior art apparatus for testing of various materials areillustrated by the following United States Letters Patent:

No. 2,599,742, issued June ice M. B. Standing et a1., Patent No.2,646,678, issued June H. L. Twining, Patent No. 2,733,959, issued Feb.7, 1956;

K. T. Norell, Patent No. 2,909,286, issued Oct. 20, 1959;

J. P. Gallus, Patent No. 3,055,208, issued Sept. 25, 1962;

H. H. Farrell et al., Patent No. 3,139,747, issued July 7,

As illustrated by the Standing et al. patent mentioned above, prior artdevices employing a removable filter medium retainer adjacent the bottomof the liquid container have not provided adequate sealing means toprevent leakage of liquid out of the container into the atmosphere.

Another disadvantage of prior art systems is their inability toautomatically maintain a constant back pressure. Generally, filtratecollects in the back pressure system causing the back pressure toincrease due to presence of the extra fluid. The excess pressuregenerated is usually relieved manually which requires that an operatorbe present at all times during the test to relieve the excess backpressure as it builds up.

Accordingly, it is an object of this invention to provide an apparatusfor filtering of liquid containing suspended solids which eliminates thepossibility of back pressure on the liquid exceeding the head pressure.

Yet another object is to provide an improved means for sealing thefiltering medium in the liquid container.

Still another object is to provide apparatus capable of automaticallyrelieving excess back pressure.

The invention may be described generally as an apparatus for removingsolids from a liquid under differential pressure, which apparatusincludes container means for containing the liquid under pressure, meansfor filtering solids from the liquid and means for introducingcompressed gas into the container means for generating a head pressureon the liquid, which apparatus additionally includes the improvementcomprising: first means serving to communicate gas generating headpressure on the liquid with the filtration means for generating a backpressure on the liquid; and second means associated with the first meansfor maintaining a lower back pressure than head pressure on the liquid.

To be more specific, reference is now made to the drawings.

In the drawings:

FIGURE 1 is a schematic illustration of one embodiment of the invention,

FIGURE 2 is a partial cutaway cross-sectional view of the liquidcontainer of FIG. 1 illustrating the filter medium retaining means,

FIGURE 3 is an enlarged partial cutaway cross-sectional view of theneedle valve illustrated in FIG. 2.

Referring now particularly to FIGS. 1 and 2, cylindrical container means1 is provided for containing a fluid, such as a drill mud or the like,which has suspended solids. Container 1 is preferably formed of a metal,such as stainless steel, which is capable of withstanding pressures onthe order of 1000 pounds per square inch. Container 1 is providedproximate its lower end with an annular recess 2 which terminates atannular shoulder 3. Recess 2 is adapted to receive cup member 4 whichhas a circular peripheral configuration. Cup member 4 is provided with acircular lip 5 which defines a recess adapted to receive a filter medium6 which is comprised of filter paper 7 which overlies a perforate screenmaterial 8. Obviously, other type filter media may be utilized. Abovecup 4, wall 59 of container 1 defines a chamber 9 for containing a testspecimen of a liquid to be filtered.

To sealingly retain a liquid within container 1, a resilient seal meansis provided such as a quad-ring 11 which, as illustrated, resembles afour-leaf clover in crosssection. An O-ring or the like may be used, buta quadring is preferred. Quad-ring 11 overlies the periphery of filtermedium 6 and engages both lip and shoulder 3 which, as illustratedparticularly by FIG. 2, proximately abut. To assure sealing engagementof quad-ring 11 with shoulder 3 and lip 5, cup member 4 is retainedwithin recess 2 by means of a C-ring 12, which may be outwardly beveledas shown. C-ring 12. is accommodated in an annular groove 13 provided inwall 59 of container 1. Annular groove 13 may form a surface inclinedradially outwardly toward the shoulder portion of recess 2 to permitC-ring 12 compressingly retain cup 4 in recess 2 upon insertion ofC-ring 12 to compressingly retain cup 4 in recess 2 upon insertion ofC-ring 12 in groove 13. C-ring 12 and groove 13 may be provided withoutthe bevels shown in the drawing, and other retaining means may besubstituted to hold cup 4 in place in recess 2.

Cup 4 is provided with a passageway 14 which communicates at its upwardend with the recess formed by lip 5 and its lowermost end with anopening 15 defined by nipple 16. Threadably engaged with nipple 16through threads 17 is a needle valve 18 provided with a conical tip 19.

The conical tip 19 upon full engagement of needle valve 18 with nipple16 engages passageway 14 as illustrated in FIG. 3 to block fluidcommunication therethrough. Rotation of needle valve 13 to move valve 18downward as viewed in FIG. 3 will permit communication betweenpassageway 14 and passageways 21 which converge into passageway 22. Toprevent the leakage of fluid contained in the chamber 15 around threads17, an O-ring 23 is carried within groove 24 in needle valve 18 forsealingly engaging needle valve 18 with the interior wall 25 of nipple16.

Referring back to FIG. 1, means are provided for establishing adifierential pressure across fluid in container 1. These means include apressure source such as the cartridge of pressurized gas 26 whichcommunicates through conduit 27 with the inlet port 28 of a conventionaladjustable constant pressure discharge regulator 29. Regulator 29 isadapted to reduce pressure applied to its inlet port 28 and apply thereduced pressure to its discharge port 31. Regulator 29 communicatesthrough conduit 32 with chamber 9 of container 1 for applying a headpressure to any liquid contained therein. Conduit 32 is provided with .acoupling 30 of conventional design to permit removal of regulator 29from container 1. Discharge port 31 of regulator 29 also communicatesthrough conduit 33, needle valve 34 and conduit 35 with the port 36 of aconventional adjustable constant pressure discharge regulator 37.Regulator 37 is provided with another port 38 which through conduit 39communicates with a filtrate receiver 41 which is preferably formed of ametal, such as stainless steel, capable of sustaining pressures on theorder of 1000 pounds per square inch (p.s.i.).

Filtrate receiver 41 is provided with conduit means 42 whichcommunicates at its bottom end with the bottom of filtrate receiver 41and at its uppermost end with needle valve 18 which is schematicallyillustrated in FIG. 1. Any suitable type of coupling can be used toconnect needle valve 18 and conduit 42. Needle valve 18, as explainedbefore, communicates through cup 4 and filter medium 6 with chamber 9 ofcontainer 1. Conduit means 42 communicates through conduit 43, needlevalve 44 and conduit 45 with the exterior of filtrate receiver 41.Conduit 45 conveniently terminates in a graduated cylinder 46.

To permit gauging of pressures applied through discharge port 31 ofregulator 29, a conventional pressure gauge 47 is provided whichcommunicates with discharge port 31 through a conduit 48. Similarly,pressure applied through port 38 of regulator 37 may be sensed throughuse of a conventional pressure gauge 49 which communicates with port 38through conduit 51. Regulator 37 is preferably provided withconventional mean for relieving pressure at its port 38 when thepressure at port 38 exceeds a predetermined pressure. Gas generating theexcess pressure at port 38 is relieved to the atmosphere through aconduit 52 which terminates in a bubble trap 53 which is filled with aliquid 54 such as water and vented to the atmosphere through an opening55.

Means are also provided for rinsing the temperature of the test specimenabove atmospheric temperature. These means conveniently take the form ofa conventional thermostat controlled power source 56 which drives aheating element 57 disposed about container 1. Visual perception oftemperature in container 1 is permitted by use of a conventionalthermometer 58 which is carried within a recess (not illustrated) withinwall 59 of container 1.

In operation, container 1 is filled with a test specimen of a liquidcontaining suspended solids such as a drill mud by disconnectingcouplings 30 and 40, removing and inverting container 1, removingbeveled C-ring 12, cup 4, filter medium 6 and quad-ring 11. A cap (notillustrated) may be placed over coupling 30 to prevent flowtherethrough, and then container 1 is filled with a test specimen ofliquid. After filling of chamber 9 with the liquid, the quad-ring 11,filter medium 6 and cup 4 are inserted in recess 2 as illustrated inFIG. 2. C-ring 12 is then radially compressed, placed in recess 2 andpermitted to expand into groove 13 as illustrated in FIG. 2 forcompressingly retaining cup 4 in recess 2. Valve 18 is fully engaged toblock passageway 14 and prevent loss of fluid through passageway 14 whencontainer 1 is again inverted and placed in the position illustrated inFIG. 1. After removal of the cap (not illustrated) the couplings 30 and40 are connected. Valves 34 and 44 are closed to prevent communicationtherethrough as are regulators 29 and 37. Gas cartridge 26 is thenpunctured, releasing gas to inlet port 28 of valve regulator 29.Regulator 29 is then adjusted to apply a relatively small head pressureto liquid in container 1, for example, pounds per square inch, to assurethat cup 4 has been properly inserted and no fluid leakage will occurabout quad-ring 11. The temperature of the liquid is then brought to apredetermined level by operation of theremostat controlled power source56. Regulator 29 is then adjusted to apply a predetermined head pressureon liquid in container 1, for example 1000 psi. The amount of pressurebeing applied can of course be determined by viewing of gauge 47.

Valve 34 is then opened permitting communication of regulator 37 withthe discharge port 31 of regulator 29. Regulator 37 is then adjusted toa predetermined pressure level, for example 200 p.s.i., which will bereflected by gauge 49. Valve 18 is opened permitting the pressureapplied at port 38 of regulator 37 to apply a back pressure throughpassageway 14 on the liquid in container 1. When the desired backpressure is reached, valve 34 is closed. Since the head pressure will begreater than the applied back pressure, liquid in container 1 will flowthrough filter medium 6, depositing solids thereon, and the filteredliquid or filtrate will pass through passageway 14 and into filtratereceiver 41 through conduit 42. As filtrate receiver 41 begins to fill,the back pressure on the liquid in container 1 will increase above thepredetermined discharge pressure of regulator 37 due to the confinementof gas creating back pressure. Regulator 37 through the relief meansprovided therein will relieve this excess pressure into bubble trap 53to maintain a constant back pressure. An indication of amount offiltrate being retained in filtrate retainer 41 can be gained byobserving the amount of gas flow through bubble trap 53.

When a desired filtration period has elapsed, valve 18 is closed andvalve 44 opened to permit pressure in filtrate retainer 41 to forcefiltrate contained in the receiver 41 through conduit 43, valve 44 andconduit 45 into graduated cylinder 46 where the volume of filtrate canbe measured.

If, at the end of a test it becomes necessary or desirable to removeregulator 29 from container 1 before cooling of the test specimen iscompleted, valve means (not shown) may be provided between regulator 29and container 1 to close communication therebetween after filtration ofa liquid is completed. By closing these valve means before reduction ofhead pressure, the pressure in container 1 can be maintained duringcooling of liquid therein to prevent boiling of the liquid which mayoccur if head pressure is reduced before the liquid cools.

Because both the head pressure applied to the fluid in container 1 andthe back pressure applied through passageway 14 are derived from thedischarge port of regulator 29, the possibility of back pressureexceeding head pressure is eliminated. Thus, possibility of damage tothe head pressure regulator due to discharge of liquid out of container1 is eliminated. Additionally, only one pressure generating source isnecessary to create a differential pressure across a test specimen ofliquid. Because an operator can with reasonable accuracy determineamount of filtrate being collected by viewing bubble trap 53, no glassor plastic level gauges are needed and danger to operators fromshattered glass or plastic is eliminated. Additionally, because thefiltrate receiver can be constructed entirely of metal, the size of thecontainer to hold a given volume of liquid can be reduced since glassordinarily employed to contain routine pressure is of necessity quitethick.

Gas cartridge 26 which may containe carbon dioxide, nitrogen, or thelike may be of any conventional type such as thOSe manufactured byWalter Kidde Company. Regulator 29 may conveniently be a series 1100regulator sold by Air Reduction Company, and regulator 37, includingrelief means, may be a type 16-003 manufactured by the C. A. NorgrenCompany. Pressure gauges 47 and 49 may be of any conventional type suchas those solid by Air Reduction Company. While rather specific termshave been used to describe one embodiment of the invention, they are notintended nor should they be construed to limit the scope of theinvention as defined by the appended claims.

What is claimed is:

1. In filtration apparatus for removing solids from a suspension thereofin liquid under pressure of the type including a container forcontaining the suspension under pressure, the improvement comprising:

a container having an open end which is provided with an annular recessthat terminates in an outwardly facing shoulder;

a cup member which conforms in peripheral configuration to saidcontainer recess for insertion therein;

the cup member having a lip which proximately abuts said shoulder uponinsertion of the cup member into said container recess, said cup memberlip also defining a cup recess adapted to receive a filter medium acrossthe bottom thereof;

a filter medium within said cup recess;

resilient seal means disposed to overlie said filter medium about itsperiphery adjacent said lip and extending beyond said lip for securingsaid filter medium in said cup recess and sealingly engaging both saidlip and said shoulder;

and means for retaining said cup member in said container recess withsaid seal means comprising an annular groove around said recess and ringmeans inserted into said annular groove to bear inwardly against saidcup member.

2. The apparatus of claim 1 wherein said ring means and annular grooveinclude cooperating bevel surfaces Whereby said ring means retains saidcup member compressively in said container recess.

References Cited UNITED STATES PATENTS 2,784,843 3/1957 Braunlich210-446 X 3,160,000 12/1964 Mosher 210446 X 3,250,395 5/1966 Blume210-451 X SAMIH N. ZAI-TARNA, Primary Examiner.

